Music and lyrics by William Finn. Book by William Finn and James Lapine. Directed by Peter Jorgensen. Coproduced by Wizard Productions and the Chutzpah! festival. At the Norman Rothstein Theatre on Saturday, February 12. Continues until February 20

During Act 1, I was impressed but alienated. By Act 2, I was weeping.

Falsettos tells the story of Marvin, who leaves his wife Trina and their 10-year-old son, Jason, to be with his male lover, Whizzer. Not to be outdone, Trina marries Marvin’s psychiatrist, Mendel.

The first act bombards the audience with musical complexity and New York Jewish neuroses. Marvin and Whizzer sing, “Of all the lesser passions, we love fighting most.” They do a lot of it. So do Trina and Marvin. Clearly, Mendel is wildly unethical, so the googly eyes he makes at his client’s ex-wife are less than charming.

Very little tenderness emerges until the end of the act, when Marvin sings to Jason, who has been worried that his father’s homosexuality might be heritable: “Sing for yourself as we march along/A man, kid, you’ll be, kid, whatever the song.”

Fortunately, Act 2, which was written nine years after Act 1, is more generous-hearted. (Falsettos combines two one-act musicals: March of the Falsettos, which premiered in 1981, and Falsettoland, which premiered in 1990.) The second act has two emotionally rich focuses: Jason’s coming of age as symbolized by his bar mitzvah, and the emergence of AIDS. In one of the most satisfying numbers of the evening, all of the adults show up for Jason’s Little League game to watch “Jewish boys who can’t play baseball play baseball”. As AIDS touches their lives, Marvin and Whizzer’s love becomes more tender than combative.

Although Act 2 of this sung-through musical is more melodic than Act 1, the score throughout is dauntingly complex. A couple of the performers in this production nail the material. Linda Quibell plays Dr. Charlotte, one of Marvin and Whizzer’s lesbian next-door neighbours. In “Something Bad Is Happening”, Charlotte notices that too many bachelors are getting sick. Throughout the song’s tricky intervals, Quibell is pitch-perfect, and she plays the musical and emotional dynamics so expertly that the number is a knockout.

Catriona Murphy is also right on the money as Trina. Murphy is vocally assured and, emotionally, she conveys exactly the combination of brittleness and vulnerability that this material demands—especially when she sings, in Act 1, “I’m tired of all the happy men who rule the world.” Eleven-year-old Harrison Ivaz also impresses mightily as Jason. (Ivaz alternates this role with Yaakov Bellas.) Try singing a couple of bars of the score and you’ll realize how good this guy is.

Liam Kearns shows less stage presence than you’d hope for as Marvin. Tyson Coady is more charismatic as Whizzer, but the emotional world created by these two is disappointingly flat and, although they are good singers, they’re not always up to this tricky material. Robert Clarke is vocally precise and, once he stops leering, he makes a charming Mendel.

Amir Ofek contributes a bold set design: huge black-and-white photographic portraits of the characters hang in a semi-circle at the back of stage, just in front of Kerry O’Donovan’s excellent four-piece band. I shed a lot of tears during Act 2—as anyone who remembers or can imagine AIDS in 1981 will—but it was a staging moment involving the set, a delicate indication of death, that really did me in.